Normalization of Cross Sections for Charge-Transfer Collisions Producing Metastable (2S) Hydrogen Atoms

Abstract

Reported measurements of the cross section for the production of metastable hydrogen atoms in the $2S$ state are compared to theoretical predictions for charge-transfer collisions between protons and helium and atomic hydrogen. The magnitudes of the cross sections for some of the experimental data are arbitrarily adjusted to produce a consistent energy dependence of the reaction cross sections. Agreement between recent theoretical predictions and experiment is then found to be excellent, leading to the conclusion that for these excited-state charge-transfer reactions, the Born approximation is not a valid description, even at projectile energies above 100 keV.